Problem: Simplify the following expression: $z = \dfrac{-6t}{3} + \dfrac{3t}{3}$
Since the expressions have the same denominator we simply combine the numerators: $z = \dfrac{-6t + 3t}{3}$ Combine like terms: $z = \dfrac{-3t}{3}$ Simplify by dividing numerator and denominator by 3: $z = \dfrac{-t}{1}$ $z = -t$